Principal Investigator: Mrs Maria Borges

1a: We aim to improve the understanding on whether low maternal vitamin D levels and high maternal body mass index (BMI) can contribute to developing adverse outcomes during and after pregnancy, such as gestational diabetes, miscarriages, stillbirth, need for caesarean, low birth weight and longer hospital stays after delivery.

1b: Investigating the influence of maternal BMI and vitamin D levels on pregnancy-related adverse outcomes fits with the central aim of UK Biobank to improve prevention and treatment of diseases.

1c: For this study, we will use data on BMI, vitamin D levels, genetics, and obstetric-related outcomes in all women that have ever being pregnant. We will compare women with different genetic makeups related to vitamin D and BMI using a technique named Mendelian randomisation to assess whether low maternal vitamin D levels or high maternal BMI are likely to increase the risk of developing adverse pregnancy-related events.

1d: Data will be requested for females only (n < 273,000)

Original scope:

To improve the understanding on whether low maternal vitamin D levels and high maternal body mass index (BMI) can contribute to developing adverse outcomes during and after pregnancy, such as gestational diabetes, miscarriages, stillbirth, need for caesarean, low birth weight and longer hospital stays after delivery.

New scope:

A range of maternal risk factors are increasingly hypothesised to cause pregnancy and perinatal adverse outcomes but with limited evidence regarding which are causal. Understanding whether maternal exposures influence or are simply correlated with adverse outcomes during and after pregnancy is essential to inform interventions aimed to improve maternal and child health.

Our initial proposal aimed, by using Mendelian randomisation, to investigate the effects of BMI and vitamin D on adverse pregnancy and perinatal outcomes. We have previously proposed to extend this approach by using Mendelian randomization to interrogate a much broader range of maternal factors that might be relevant for adverse pregnancy and perinatal outcomes, such as smoking, sleep patterns, diet, alcohol and coffee intake (approval granted in November 15th, 2017). Exploring the impact of a wider range of maternal risk factors on multiple adverse pregnancy and perinatal outcomes will be of greater relevance to clinical practice and policy making. UKB is unique in its size and scale for addressing these questions that are of importance to pregnancy and perinatal health.